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Hey hit_em,
Yes, you can weld black iron fairly well if you take some time to prep.. Is this pipe or old black-iron furniture? The safest way to repair black iron is with oxy/acet. and using silver-solder. If you want to weld it, you must prep the weld area with a grinding wheel or sanding disc, brush with acetone or toluene to degrease, pre-heat the weld area to at least 250 deg.(I use oxy/acet. with a rosebud). I MIG my black iron repairs with ER70S-6, C-25 @ 18CFH, and tack each end, then manually do a pulse-like feed of the wire to maintain heat. After the weld is finished, I apply the rosebud again to maintain a slow reduction of heat. You can also totally cover the weld area in white sand to slow cooling rate. This will generally work well to keep the black-iron from cracking. Must cool very slowly. Hope that helps a bit....Denny

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I'm talking about black iron pipe, the stuff you can get at any hardware store. I want to weld the pipe and fittinigs together. But I think the fittings might be cast iron can this be welded? The reason I'm wanting to do this is I dont have a pipe bender to make a 90 degree corner. does anyone know anything else I can do?

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Back in the old days most of the local racers got away with black iron pipe. In the 60's and 70's they just used a stick welder, then in the 80's everyone was migging it. Black iron pipe has been banned in racing for many years now but was commonly used and welded in the past. As for welding fittings to it I have done it with both stick and mig with good results. Dave

If necessity is the Mother of Invention, I must be the Father of Desperation!

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it's going to be pipe thats goes on the bottom of a barge for anti freeze to run through it and gets cooled down from traveling in the water so there has to be like 6 runs of 15' for each engine. this is why I need to turn 180 degrees. does this make sense? so can the pipe and fittings be welded together? I think the fittings are cast iron, can anyone verify this? if it is cast then wont they crack after a period of time?

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it's going to be pipe thats goes on the bottom of a barge for anti freeze to run through it and gets cooled down from traveling in the water so there has to be like 6 runs of 15' for each engine. this is why I need to turn 180 degrees. does this make sense? ...

There must be some reason that you don't want to use regular 90* elbows to build up the returns???

Tom Veatch
Wichita, KS

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I dont know where t get 90 degree angles or else that is what I would do. the only thing close I have found are the quick fab squaretubing elbows, but the guy wants round tubing and I dont kow where to get elbows and I dont have a bender. I'm openedto suggestions I was just considering this way as an option.

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this black iron pipe your talking about sounds to me like black pipe (plumbing pipe painted black, bevled at both ends ushally), wich is just mild steel, they also make mild steel weldable elbow's to weld to black pipe

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Sounds as if what you're doing is what we refer to as a keel cooling system. If you're planning to operate this vessel in salt water, you may as well forget about using the pipe you're talking about. It won't last a season in salt water.

A much better option (one we've used for years) is to use copper pipe and solder the 90 angles in. The size of the engine will determine the length and number of runs.

The copper will last longer in salt water and is also a better conductor of the heat you're trying to displace.

If you gave me some more info concerning HP, gas or diesel, and where you'll be operating, I'll give you a wag at how many linear feet of tubing will be required.